An apparatus for inflating an inflatable vehicle occupant restraint, such as an air bag, includes an inflator which comprises a source of inflation fluid for inflating the air bag. The source of inflation fluid may include, for example, an ignitable gas generating material which generates a large volume of gas when ignited. When the vehicle experiences deceleration of at least a predetermined amount which indicates the occurrence of a vehicle collision, the gas generating material is ignited. The gas which is then generated upon combustion of the gas generating material is directed to flow from the inflator into the air bag to inflate the air bag. When the air bag is inflated, it extends into the vehicle occupant compartment to restrain an occupant of the vehicle from forcefully striking parts of the vehicle.
It is sometimes desirable to control the inflation of the air bag in response to various conditions. For example, it may be desirable to control the inflation of the air bag in response to the position of a vehicle occupant to be restrained by the air bag. It may also be desirable to control the inflation of the air bag in response to the ambient temperature.